FIG. 13 is a cross-sectional view showing a thin-film structural body formed by using a conventional manufacturing method of a thin-film structural body. As shown in FIG. 13, this thin-film structural body 101, which is provided with a supporting part 103 and a floating part 105 supported by the supporting part 103, is formed above a substrate 107 by using a conductive material. The floating part 105 is placed with a predetermined distance from the substrate 107, and sticks out outward from an upper portion of the supporting part 103.
The substrate 107 is provided with a substrate main body 111, a first insulating film 113 formed on the substrate main body 111, a wiring 115 selectively formed on the insulating film 113, and a second insulating film 117 selectively covering a surface of the wiring 115 and the insulating film 113.
The surface of the insulating film 113 is flat, and the wiring 115 is formed on the surface to protrude therefrom. The supporting part 103 is formed on the wiring 115 in a manner so as to cover one portion of the wiring 115. A hole 117a is formed in the corresponding portion of the insulating film 117 on which the supporting part 103 is to be formed so that the supporting part 103 is connected to the wiring 115 through the hole 117a. The film thickness of the insulating film 117 is made thin to such an extent that a step difference that is caused on the surface of the substrate 107 by the influence of the circumferential edge of the insulating film 117 becomes substantially ignorable.
In the conventional manufacturing method of a thin-film structural body, first, a sacrifice film 121 is formed on the substrate 107 having such a configuration as shown in FIG. 14. Next, a portion of the sacrifice film 121 at which the supporting part 103 is to be formed is partially removed so that, as shown in FIG. 15, an anchor hole part 121a is formed.
Successively, a thin-film layer 123 is deposited on the surface of the sacrifice film 121 and the surface of the substrate 107 exposed through the anchor hole part 121a by using a conductive material, as shown in FIG. 16.
Next, the thin-film layer 123 is selectively removed and patterned so that residual portions of the thin-film layer 123 form a thin-film structural body 101. In this case, a portion which has been fitted into anchor hole part 121a of the residual portion forms the supporting part 103, and another portion located on the sacrifice film 121 forms the floating part 105. Then, the sacrifice film 121 is removed so that a structure shown in FIG. 13 is obtained.
In such a conventional manufacturing method, in a state shown in FIG. 14, a protruding part 122a is formed on the surface 122 of the sacrifice film 121 due to the wiring 115 of the substrate 107. When such a sacrifice film 121 having the protruding part 122a is used for preparing the thin-film structural body 101, the following problems are raised.
The protruding part 122a has a slanting portion H which is located above the outer edge of the wiring 115 and which approaches the substrate 107 in a direction toward the outside of the wiring 115. With respect to the thickness of the supporting part 103, there is a limitation in that if it is too thick, reduction of space is not available, and in that if it is too thin, there might be a failure in the electrical connection between the thin-film structural body 101 and the wiring 115. Moreover, with respect to the width of the wiring 115, it needs to be thinner in order to save space, depending on its layout positions and purposes of use. For this reason, in the case of the width of the wiring 115 which is made thinner, the supporting part 103 is formed on the wiring 115 with a thickness that is almost the same as the width of the wiring 115 as shown in FIG. 13. In a corresponding manner, the anchor hole part 121a is also formed on the wiring 115 with an opening width which is almost the same as the width of the wiring 115. As a result, as shown in FIG. 15, at least one portion of the slanting portion H remains on the peripheral portion 121b of the anchor hole part 121a of the sacrifice film 121.
The surface shape of this peripheral portion 121b is reflected to the shape of the thin-film structural body 101 so that a neck portion 131 is formed at a portion corresponding to the peripheral portion 121 of the thin-film structural body 101, more specifically, a coupling portion between the supporting part 103 and the floating part 105, as shown in FIG. 13. For this reason, the thin-film structural body 101 might be damaged at the neck portion 131 by an impact or the like, resulting in degradation in the strength and reliability of the thin-film structural body 101.